1. Lecture 3 IOPs: Absorption physics and absorbing materials Collin Roesler 3 July 2007

2. Lecture Overview Overview of the electromagnetic spectrum What is absorption? Who are the absorbers? Impacts on ocean color

3. Electromagnetic Spectrum Charged particles create electric fields (oscillation between +,-) When a charged particle moves, it creates a magnetic field The electromagnetic field oscillates as the energy propagates the range of oscillation frequencies is described by the EM spectrum http://wps.prenhall.com/wps/media/objects/610/625137/Chaisson

4. Black body radiation http://aeon.physics.weber.edu/jca/PHSX1030/Images/blackbody.jpg Any object with a temperature >0 K emits electromagnetic radiation The spectrum of that emission depends upon the temperature (Planck’s Law) As T , emitted energy  (Stefan- Boltzman’s Law), and the frequency of emitted energy  (shorter wavelengths) As T , the of maximal emission  (Wein’s Law) Energy contained in a packet of EM radiation (e.g. visible photon)  with  wavelength

5. So the sun, at ~5800 K, emits primarily visible radiation (light), most of which penetrates the atmosphere

6. Light Penetration

7. What is absorption? since electromagnetic radiation is energy propagation, when materials absorb radiation, they absorb energy what happens to the molecule depends upon the wavelength (frequency)

8. Interactions between energy and matter MICROWAVE

9. The amount of energy required to move an electron to another orbital shell is quantized 400 450 500 550 600 650 700 interatomic distance

10. quantized energy states 400 450 500 550 600 650 700 interatomic distance

11. quantized vibrational states interatomic distance 400 450 500 550 600 650 700

12. The chlorophyll a molecule has two higher energy orbital shells associated with the energy equivalent of a blue (443 nm) and a red (676 nm) photon http://www.mie.utoronto.ca/labs

13. Example of absorption spectra for three environments all have strong red absorption but variable blue absorption

14. Absorbing matter a T = a w +  a dissolved compounds +  a particles Ideally…

15. Absorbing matter water chromophoric dissolved matter phytoplankton (in vivo pigments) chromophoric organic particulate matter (not pigments) chromophoric inorganic particulate matter (minerals) a T = a w + a CDM + a  + a COPM + a CIPM Practically…

16. Absorbing Components: Water variations are methodological

17. Absorbing Components: Water natural variations Pegau and Zaneveld 1993 Limnol Oceanogr. Temperature 5oC5oC 30 o C

18. Absorbing Components: Water natural variations Pegau etal. 1997 Appl.Opt. Salinity

19. Absorbing Components: Chromophoric Dissolved Matter a CDM ( ) = a CDM ( o ) exp(-S ( - o )) Kirk 1983 Carder et al. 1989 L&O

20. Absorbing Components: Chromophoric Dissolved Matter a CDM ( ) = a CDM ( o ) exp(-S ( - o )) Carder et al. 1989 L&O S 0.01 0.02 S=0.014 S=0.011 Simeon et al. 2003 JGR Equatorial Pacific

21. Absorbing Components: Phytoplankton 1989 L&O Individual cells Roesler et al. 1989 L&O Species

22. Absorbing Components: Phytoplankton Pigment Packaging impact on absorption Morel and Bricaud 1981 DSR

23. Absorbing Components: other protists Morel and Ahn 1990 JMR heterotrophic bacteria ciliates and flagellates cytochrome 412

24. Absorbing Components: organic detrital particles Iturriaga and Siegel 1989 L&O JMR

25. Absorbing Components: inorganic particles Babin and Stramski 2003 Patterson et al. 1977 JGR

26. To model the impacts of absorbing constituents…add them up

27. More on absorption CDOM absorption methods –Lecture today –Lab today Phytoplankton absorption –Lecture Thursday Particulate absorption methods –Lecture Thursday –Lab Thursday